[ARC5] T-30 throat mic.

[Richard Knoppow]

----- Original Message ----- 
From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
To: "Jim Haynes" <jhhaynes at earthlink.net>; "DSP3" 
<jeepp at comcast.net>
Cc: <arc5 at mailman.qth.net>
Sent: Tuesday, January 13, 2015 9:32 PM
Subject: Re: [ARC5] T-30 throat mic.


>
> ----- Original Message ----- 
> From: "Jim Haynes" <jhhaynes at earthlink.net>
> To: "DSP3" <jeepp at comcast.net>
> Cc: <arc5 at mailman.qth.net>
> Sent: Tuesday, January 13, 2015 10:05 AM
> Subject: Re: [ARC5] T-30 throat mic.
>
>
>> On Tue, 13 Jan 2015, DSP3 wrote:
>>> aircraft.  I asked the price of a headset for the 
>>> displayed helicopter and he told me that they were about 
>>> $2500, each.  So much for your standard D/C or $1000 
>>> Bose!!  Anyway, the T-30 is nothing special, mic-wise. 
>>> I have a couple
>>
>> Or your teenagers with their Beats headsets at $200 and 
>> up.
>
>     FWIW, I found a citation in "Acoustical Engineering" 
> Harry F. Olson to a Bell Labs Record article in the 
> edition for V.23, No.6, 1945 which covers a number of 
> military acoustical devices including the throat mic. It 
> may be found at;
> http://americanradiohistory.com/Bell_Laboratories_Record_Issue_Key.htm
>
>     Nothing much new in it but the "standard" headphone 
> described is not like any I've seen. Probably a prototype. 
> My understanding (without a reference) is that at least 
> some of the development for the familiar ear-muff style 
> pad and maybe the entire phone was done at the acoustics 
> lab at Harvard University.

     A small correction.  The illustration of the universal 
headphone is probably the ANBH-1 but the capsule is shown as 
a separate piece and the earpad is different. The ANBH-1 
phones I have are all one piece, that is, the capsule is 
either cemented or molded as part of the outer case.  The 
earpad is probably an early version, I've seen pictures of 
them bur never actually saw any. I think these must have 
been replaced with the familiar ear-muff type pretty 
quickly. The illustration is likely an engineering drawing 
of a prototype.  Its interesting to learn after so long that 
ANBH means Army,Navy,British, Headphone. And that the 
stepped case was deliberately designed in order to fit 
several existing types of headbands as well is flying 
helmets.
     BTW, the nylon flying helmets at one time were very 
cheap on the surplus market brand new. I used to get them to 
cut out the ear-muff headphone cushions. I wish I had kept a 
few intact.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com